package com.hspedu.newData.dmsxl.树.二叉树的遍历.层序遍历迭代法.队列;

import com.hspedu.newData.dmsxl.ds.TreeNode;
import org.junit.Test;

import java.util.LinkedList;
import java.util.Queue;

/**
 * @Author: yh
 * @description: 
 * @CreateTime: 2025-04-23 
 * @Version: 1.0
 */

public class LC226翻转二叉树 {

    // 迭代法
    public TreeNode invertTree(TreeNode root) {
        if (root == null) return null;
        Queue<TreeNode> queue = new LinkedList<>();
        queue.offer(root);
        while(!queue.isEmpty()){
            int len = queue.size();
            while(len>0){
                TreeNode node = queue.poll();
                swap(node);
                if (node.left != null) queue.offer(node.left);
                if (node.right != null) queue.offer(node.right);
                len --;
            }
        }
        return root;
    }

    // 递归法
    public TreeNode invertTree1(TreeNode root) {
        if (root == null) return null;

        TreeNode temp = root.left;
        root.left = root.right;
        root.right = temp;
        invertTree1(root.left);
        invertTree1(root.right);

        return root;
    }

    public void swap(TreeNode root){
        TreeNode temp = root.left;
        root.left = root.right;
        root.right = temp;
    }

    @Test
    public void test() {
        // 测试代码

        TreeNode t7 = new TreeNode(7);
        TreeNode t6 = new TreeNode(6);
        TreeNode t5 = new TreeNode(5);
        TreeNode t4 = new TreeNode(4);
        TreeNode t3 = new TreeNode(3,t6,t7);
        TreeNode t2 = new TreeNode(2,t4,t5);
        TreeNode t1 = new TreeNode(1,t2,t3);

        invertTree1(t1);
        System.out.println("==========");

    }
}
